RetrofitIQ — Building Performance Diagnostics
Building Performance Diagnostics
Certified Passive House Designer — official seal awarded to George Sora by the Passive House Institute
Passive House Institute
Certified Passive House Designer
George Sora · Verified

One Company.
One Process.
One Point of Responsibility.

We investigate, diagnose and verify the real performance of your building — heat loss, condensation, damp, air leakage, soundproofing, ventilation and indoor air quality — all under one accountable team led by a Certified Passive House Designer.

Investigate→Diagnose→Design→Remediate→Verify
Book a Survey 0753 824 3578
RetrofitIQ — Building Performance Diagnostics for Heat Loss, Condensation, Damp, Air Leakage, Soundproofing, Ventilation and Indoor Air Quality. One Company. One Process. One Point of Responsibility.
Click to book a Home Health Diagnostic Survey.
What we diagnose
Heat LossCondensationDampAir LeakageSoundproofingVentilationIndoor Air Quality
Building problems we investigate

If something feels wrong with your building — we find the root cause.

We don’t guess. Every recommendation is backed by thermal imaging, moisture readings, humidity logging, airflow measurements or pressure testing — not gut feel.

Heat Loss
Excessive thermal losses through walls, roofs and junctions.
Cold Walls
Surfaces below dewpoint that feel cold and harbour condensation.
Condensation
Surface and interstitial moisture problems.
Damp Problems
Rising, penetrating and construction-related damp.
Mould Growth
Microbial growth from sustained surface humidity.
Draughts
Uncontrolled air movement and cold spots.
Air Leakage
Unintended air paths reducing comfort and efficiency.
Poor Ventilation
Stale air, CO₂ build-up and humidity retention.
High Energy Bills
Inefficient envelopes and uncontrolled losses.
Thermal Bridges
Localised heat-loss paths through structure.
Noise Transmission
Airborne and impact noise through floors, walls, ceilings.
Overheating
Summer overheating from solar gains and poor ventilation.
Poor Indoor Air Quality
Pollutants, VOCs and inadequate fresh-air supply.
2-minute self-assessment
Do I need a Home Health Diagnostic Survey?
Educational guide
Why damp treatments often fail
The RetrofitIQ approach

One company. One process. One point of responsibility.

Most retrofit and building-performance projects involve multiple companies — an assessor, a designer, a contractor and a separate verifier. That creates communication gaps, conflicting advice and poor outcomes when no one owns the result end-to-end.

Industry standard

4 companies, 0 owners.

  • ×
    Assessor — spots symptoms
  • ×
    Designer — specifies without site context
  • ×
    Contractor — installs to a different brief
  • ×
    Verifier — tests after the fact

Gaps between stages. Nobody answerable for the final result.

RetrofitIQ model

Investigate → Diagnose → Design → Install → Verify

  • ✓
    Investigate — FLIR thermal imaging, blower door, smoke tracing, moisture mapping.
  • ✓
    Diagnose — Root cause — not symptoms.
  • ✓
    Design — Site-aware spec by a Certified Passive House Designer.
  • ✓
    Install — Our own trained team — no subcontracted gaps.
  • ✓
    Verify — Post-works re-test against measured baselines.

Single point of responsibility. One signature from problem to verified result.

Book a diagnostic survey See real projects
Real Thermal Imaging Findings

The defects we identify — measured, not guessed.

Every image below is from a real RetrofitIQ on-site survey across London and the South East. We use calibrated FLIR thermal imaging, blower door testing and moisture diagnostics to identify the root cause — then design and remediate the right intervention.

Heat Loss

Large continuous cold surfaces where heat is escaping through walls, floors and roofs faster than the heating can keep up.

Related service
Internal wall surface — uniformly cool reading (18.6 °C) recorded as part of the room-by-room baseline used to compare with warmer reference surfaces in the reportSurface Baseline
18.6 °C → 20.6 °CInternal wall surface — uniformly cool reading (18.6 °C) recorded as part of the room-by-room baseline used to compare with warmer reference surfaces in the report
Bathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finishCold Wall
15.7 °C → 22.2 °CBathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finish
Cold wall surface vs warm ceiling — significant temperature differentialHeat Loss
16.8 °C → 29.5 °CCold wall surface vs warm ceiling — significant temperature differential
Air Leakage

Cold air drawn through gaps, joints and service penetrations — visible as plumes and cold streaks under depressurisation.

Related service
Bathroom — door and reveal showing pronounced cold path with surface temperatures down to 14.5 °C, below internal dewpoint risk on cold daysAir Leakage
15.7 °C → 22.0 °CBathroom — door and reveal showing pronounced cold path with surface temperatures down to 14.5 °C, below internal dewpoint risk on cold days
Ceiling / external-wall junction — repeated cold spots along the perimeter lineAir Leakage
18.9 °C → 23.1 °CCeiling / external-wall junction — repeated cold spots along the perimeter line
Top of door frame — pronounced cold band consistent with air leakage around the lintelAir Leakage
18.1 °C → 24.2 °CTop of door frame — pronounced cold band consistent with air leakage around the lintel
Thermal Bridging

Localised cold paths where the building structure bypasses the insulation layer — lintels, reveals, slab edges and corners.

Related service
Wall / ceiling corner with vertical service pipe — concentrated cold spot at the corner junction indicating a localised thermal bridge plus a cooler signal along the pipe runThermal Bridge
19.1 °C → 21.5 °CWall / ceiling corner with vertical service pipe — concentrated cold spot at the corner junction indicating a localised thermal bridge plus a cooler signal along the pipe run
Wall / ceiling corner showing the characteristic geometric cold spot — a classic thermal bridge picked up in the assessment and flagged in the costed improvement scheduleCold Spot
19.9 °C → 22.8 °CWall / ceiling corner showing the characteristic geometric cold spot — a classic thermal bridge picked up in the assessment and flagged in the costed improvement schedule
Wall / floor junction — cooler band where the slab meets the wall, evidence of perimeter heat-loss path that the report recommends targeting with perimeter insulationFloor Junction
20.3 °C → 26.7 °CWall / floor junction — cooler band where the slab meets the wall, evidence of perimeter heat-loss path that the report recommends targeting with perimeter insulation
Missing Insulation

Large continuous cold zones — typically lofts, eaves and dwarf walls — where the insulation has slumped, gone missing or was never installed.

Related service
Loft / eaves zone — missing or compressed insulation visible as cold areaMissing Insulation
17.9 °C → 24.7 °CLoft / eaves zone — missing or compressed insulation visible as cold area
Condensation Risk

Surfaces measured below the room's dewpoint — the exact locations where condensation, black mould and damp will keep returning.

Related service
Bathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finishCold Wall
15.7 °C → 22.2 °CBathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finish
Wall / ceiling corner showing cold spot at the junction lineCold Bridge
14.6 °C → 40.4 °CWall / ceiling corner showing cold spot at the junction line
Cold wall mapped against warm radiator and surrounding fabricCold Wall
16.8 °C → 24.2 °CCold wall mapped against warm radiator and surrounding fabric
Moisture-Related Defects

Cooler surface signals corroborated with moisture-meter readings — separating condensation from rising or penetrating damp.

Related service
Bathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finishCold Wall
15.7 °C → 22.2 °CBathroom external wall — surface clearly below the rest of the room (cold reveal + cold corner) creating an elevated condensation risk on the painted finish
Cold wall mapped against warm radiator and surrounding fabricCold Wall
16.8 °C → 24.2 °CCold wall mapped against warm radiator and surrounding fabric

Surface temperatures captured with a calibrated FLIR thermal imaging camera under stabilised conditions. Investigate → Diagnose → Design → Remediate → Verify.

How we work — Investigate → Diagnose → Design → Remediate → Verify

A five-step Building Performance Diagnostics process.

One Company. One Process. One Point of Responsibility. We follow a structured engineering process so nothing slips through the gaps — from first investigation to verified, documented improvement.

STEP 01
Investigate

Site visit, visual inspection, listening to your concerns and capturing the full picture of how the building is performing.

STEP 02
Diagnose

Thermal imaging, blower door testing, moisture, humidity, ventilation and acoustics — measured data to identify the root cause, not just the symptom.

STEP 03
Design

Building-physics-led specification of the right remediation: insulation, airtightness, ventilation, soundproofing or envelope upgrades.

STEP 04
Remediate

Carry out the works correctly using appropriate materials, detailing and Passive House principles — one accountable team from start to finish.

STEP 05
Verify

Re-test, re-measure and document the improvement so the result is provable, not assumed.

Our specialist services

Diagnostics, retrofit, envelope systems, ventilation and acoustics — under one roof.

Pick the service that matches your situation, or book a Home Health Diagnostic Survey and we’ll recommend the right one.

01 / Diagnostics

Diagnostics

Building diagnostics, thermal imaging, blower door testing and forensic investigations to identify the root cause of damp, heat loss, condensation and ventilation problems.

  • Home Health Diagnostic Surveys
  • Blower Door Testing
  • Thermal Imaging Surveys
  • Moisture Investigations
  • Damp Investigations
  • Condensation Assessments
  • Mould Investigations
  • Heat Loss Analysis
02 / Insulation & Retrofit

Insulation & Retrofit

Targeted insulation and retrofit upgrades based on measured data — designed using Passive House principles to deliver real, verified performance.

  • Internal Wall Insulation
  • Loft Insulation
  • Floor Insulation
  • Roof & Ceiling Insulation
  • Thermal Bridge Reduction
  • Airtightness Improvements
  • Retrofit Planning
  • Building Performance Upgrades
03 / External Envelope & Cladding

External Envelope & Cladding

Specialist external wall insulation, ventilated façade and cladding systems for long-term durability, thermal performance and aesthetic upgrades.

  • External Wall Insulation
  • Ventilated Façade Systems
  • Cladding Systems
  • Building Envelope Improvements
  • Weatherproofing Solutions
  • Thermal Performance Upgrades
04 / Ventilation & MVHR

Ventilation & MVHR

Mechanical ventilation with heat recovery (MVHR) design advice and ventilation strategies that protect indoor air quality and building fabric.

  • Ventilation Strategy Advice
  • MVHR Design Advice
  • Airflow Calculations
  • Duct Route Planning
  • Equipment Recommendations
  • Indoor Air Quality Improvements
  • Heat Recovery Ventilation Solutions
05 / Soundproofing & Acoustics

Soundproofing & Acoustics

Acoustic surveys and full soundproofing systems for airborne and impact noise across walls, floors and ceilings — assessed, designed and verified.

  • Soundproofing Assessments
  • Acoustic Surveys
  • Impact Noise Reduction
  • Airborne Noise Reduction
  • Acoustic Floor Systems
  • Acoustic Wall Systems
  • Acoustic Ceiling Systems
  • Full Room Acoustic Upgrades
What we do, in depth

Measured building performance for London homes.

RetrofitIQ combines diagnostics, design and installation under one roof. Every survey starts with measurement — not assumption — so the spec you receive is targeted at what your home is actually doing.

Building Performance

How a home actually performs under real heating, weather and moisture loads — measured, not estimated.

Home Health Diagnostics

A full-fabric assessment combining thermal imaging, airtightness testing, moisture mapping and indoor air-quality readings.

Thermal Imaging Surveys

Calibrated FLIR imagery to find heat loss, thermal bridges, missing insulation and condensation risks before they cause damage.

Blower Door Testing

Measured airtightness in air changes per hour at 50 Pa (n50/q50) — plus smoke tracing to locate every leak pathway.

Condensation & Moisture

Surface temperature + relative humidity + dewpoint margin analysis — the only way to distinguish condensation from rising and penetrating damp.

Passive House Design

Certified Passive House Designer credentials — applied to new-build and EnerPHit retrofit projects.

Retrofit Consultancy

Internal Wall Insulation, External Wall Insulation, loft and underfloor systems specified by measurement, not assumption.

Indoor Air Quality

CO₂, humidity, VOC and ventilation-rate readings to protect occupant health, especially in airtight retrofitted homes.

London Coverage

Greater London + South East — terraces, conversions, mansion blocks, new-build flats and EnerPHit projects across every borough.

Customer Feedback

Verified reviews from Checkatrade and MyBuilder.

Real reviews from real homeowners, landlords and tenants — left directly on our public Checkatrade (3 reviews) and MyBuilder (5 reviews) profiles. Each card preserves the original customer text and adds a short professional summary of the project completed.

CT
Checkatrade
View profile →
MB
MyBuilder
View profile →
CTVerified on Checkatrade
Soundproofing — acoustic floor build-up across multiple rooms + wall upgrade
N17, London · Posted June 2026
“Excellent Service. Highly recommended. The work was done to perfection. We were always kept informed of what was happening and given advice of the best cost effective option. Anyone who choses this company will not be disappointed. They are extremely professional and good value for money. We will be using them again to do some more work. Thank you GAS.”
Project summary

Whole-floor acoustic upgrade across multiple rooms in an N17 home — existing finishes stripped, RW5 acoustic mineral wool installed between joists, decoupling treatment applied to the floor structure, new floorboards laid, acoustic underlay + new carpet finished. One bedroom received an additional acoustic wall upgrade. Outcome: a measurably quieter home and a 10/10 review.

Verified Checkatrade customer
CTVerified on Checkatrade
Underfloor insulation
E17, London · Posted 05 April
“George was brilliant. We required the existing floor to be lifted and insulation installed. Throughout the process George was tidy, considerate and offered advice on how to achieve the best outcome. The team documented the process throughly with photos for my records. I would definitely use GAS again for similar works or general construction in our home.”
Project summary

Suspended-timber underfloor insulation upgrade — lifted finished floor, installed continuous insulation between joists, fully documented with photographs. Outcome: warmer floors, reduced heat loss and a clean, well-documented retrofit the client is happy to reuse.

Luke Large
CTVerified on Checkatrade
Property assessment & costed improvements report
IG8, London · Posted 13 March
“George was friendly, arrived on time and was very helpful during the assessment. He answered all of my questions and showed a passion for what he does. The report provided was very thorough and George was able to provide full costings for all proposed improvements to my flat. I highly recommend him!”
Project summary

Whole-flat Home Health Diagnostic assessment with a thorough written report and a fully-costed schedule of improvement options. Outcome: clear evidence-based plan the client can prioritise and budget against.

Verified Checkatrade customer
CTVerified on Checkatrade
Multi-trade renovation works (occupied property)
SG6 · Posted 06 February
“Very professional, communicated clearly throughout the project, and paid close attention to detail. We were moving in the middle of the works, while also working from home, and George made sure to always work around us, prioritise things that would help us and keep things tidy in the house. Very knowledgeable and friendly, already booked for more projects!”
Project summary

Sensitive multi-trade renovation programme delivered while the client was moving in and working from home. Outcome: minimal disruption, tidy site, and a relationship strong enough that the client booked further works.

Verified Checkatrade customer
MBVerified on MyBuilder
Investigation of moisture / paint swelling around internal window
Orpington · 17 Feb 2026
Project summary

Diagnostic investigation of moisture and paint swelling around an internal window reveal. Surface moisture, dewpoint and thermal imaging used to identify the source (cold reveal + interstitial condensation) and recommend a remediation plan.

MyBuilder user from Orpington
MBVerified on MyBuilder
Replace insulated ventilation duct hose in loft
Greenwich, London · 10 Feb 2026
Project summary

Replaced a damaged insulated ventilation duct hose in the loft, restoring efficient warm-air movement, preventing condensation inside the duct and protecting the loft insulation from moisture damage.

MyBuilder user from Greenwich, London
More feedback

See the full set of verified reviews.

All reviews
Diagnostic Equipment

Measured data. No guesswork.

Calibrated, professional-grade equipment used in every diagnostic survey.

EQ-01
FLIR Thermal Camera
Infrared surveys to map heat-loss, missing insulation and thermal bridges.
EQ-02
Blower Door Testing System
Pressure-tested airtightness measurement at 50 Pa.
EQ-03
Moisture Meter
Surface and deep moisture readings across substrates.
EQ-04
Smoke Tracing Equipment
Visualises air-leakage paths and ventilation behaviour.
EQ-05
Ventilation Assessment
Airflow measurements for extract, supply and MVHR systems.
Passive House Principles

Building science that actually works.

We apply Passive House principles to every project — even where full certification isn’t the goal — because they deliver measurable, predictable comfort, energy use and health outcomes.

Designer
George Sora — Certified Passive House Designer
PRINCIPLE 01
Superinsulation

High-performance insulation across walls, roofs and floors to minimise heat loss.

PRINCIPLE 02
Airtight Construction

Controlled airtightness, measured and verified by blower door testing.

PRINCIPLE 03
Thermal Bridge Reduction

Continuous insulation detailing to eliminate localised heat-loss paths.

PRINCIPLE 04
High-Performance Windows & Doors

Triple-glazed and insulated frames to balance comfort and daylight.

PRINCIPLE 05
Mechanical Ventilation with Heat Recovery

Constant fresh air with up to 90% heat recovery.

PRINCIPLE 06
Measured & Verified Performance

Quantified results — not assumptions — through testing and monitoring.

Free Guide · PDF Download

5 Signs Your Home Is Losing
Energy, Comfort and Indoor Air Quality.

A diagnostics-led guide for homeowners, landlords, architects and property managers — by a Certified Passive House Designer. Includes the five Passive House principles and our five-step Building Performance Diagnostics process.

01Excessive Heat Loss
02Air Leakage & Draughts
03Condensation & Mould Growth
04Poor Ventilation & Indoor Air Quality
05Thermal Bridges & Cold Surfaces
Get the free PDF

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Investigate • Diagnose • Design • Remediate • Verify

Ready to find out what’s actually going on with your building?

Book a Home Health Diagnostic Survey or send us photos of the issue — we’ll get back to you with a clear next step.

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